JP2015102541A - Environmental test device and cooling system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an environmental test device which is a cooling system enabling switching between one way operation and two way operation and hardly reducing a cooling capacity in switching with less change gradient in temperature as compared to the prior art.SOLUTION: A cooling system 7 includes: a low temperature side freezing circuit 20; and a high temperature side freezing circuit 21. The cooling system 7 can switch between one way operation and two way operation. When switching from one way operation to two way operation, a transition operation is temporarily executed, which makes a refrigerant pass through both of an evaporation part 33 for cooling an interior of a tank and an evaporation part 35 for cooling a capacitor. The transition operation makes the refrigerant pass through both of a main circuit 50 and an auxiliary circuit 51 of the higher temperature side freezing circuit 21, and in this state, the refrigerant is also circulated in the low temperature side freeing circuit 20. The transition operation is performed stepwise, and flow passages passing through five capillary tubes 41, 42, 43, 44, and 45 which constitute an expansion passage 36 for cooling the interior of the tank are completely opened at the beginning, and these passages are closed one by one as time elapses.

Description

The present invention relates to an environmental test apparatus. More specifically, the present invention has a plurality of refrigeration circuits including a compressor, a condenser, expansion means, and an evaporator, and operates in a single unit using only one refrigeration circuit. And an environmental test apparatus including a cooling device capable of switching between two-way operation in which two or more refrigeration circuits are connected.
The present invention also relates to a cooling device capable of switching between one-way operation and two-way operation.

  Generally, a cooling device is mounted on an environmental test apparatus. The cooling device includes a compressor, a condenser, expansion means, and an evaporator, and has a refrigeration circuit in which a phase-change refrigerant circulates. In the refrigeration circuit, the refrigerant is compressed by the compressor, condensed by the condenser, expanded by the expansion means, evaporated by the evaporator, and returned to the compressor again. And when a refrigerant evaporates with an evaporator, it takes heat from the circumference.

Many of the cooling devices employed in the environmental test apparatus are structured by a set of a compressor, a condenser, an expansion means, and an evaporator and are cooled by a refrigeration circuit.
When a lower temperature is required, a cooling device that performs two-way operation by thermally connecting two or more refrigeration circuits with a cascade condenser is used.
The cooling device that performs the dual operation has a plurality of refrigeration circuits. A cooling device that performs dual operation has a high-temperature side refrigeration circuit and a low-temperature side refrigeration circuit, and an evaporator of the high-temperature side refrigeration circuit and a condenser of the low-temperature side refrigeration circuit are integrated to form a cascade capacitor.
According to the cooling device that performs dual operation, the condenser of the low-temperature side refrigeration circuit is further cooled, and a cryogenic temperature can be created.

  By the way, if cooling is performed in a two-way operation, the cooling capacity at a low temperature is increased, but a plurality of refrigeration circuits are operated, so that power consumption is large. Therefore, when a very low temperature is not required, that is, when it is desired to create a moderately low temperature environment, it is desirable to operate the cooling device using only one set of refrigeration circuits. That is, when it is desired to create a moderate low temperature environment, it is desirable to operate the cooling device in a single operation.

  Patent Document 1 discloses a cooling device capable of switching between a one-way operation and a two-way operation.

Japanese Patent Laid-Open No. 2001-174381

The environmental test equipment is used to perform various types of tests. In some cases, the DUT is exposed to a certain temperature environment, or the performance of the DUT is tested by changing from a high temperature environment to a low temperature environment. . In the case of testing by changing from the latter high temperature environment to the low temperature environment, it is desirable that the temperature change gradient is constant.
Here, when using a cooling device capable of switching between one-way operation and two-way operation, for example, when changing the inside of the tank to a low temperature such as 150 degrees Celsius to minus 40 degrees Celsius, The operation is started, and the operation is switched to the dual operation on the way. That is, when the temperature in the tank is high, the cooling device is operated in a unitary operation, and when the temperature in the tank is lowered to some extent, the operation mode is switched to a dual operation and finally reaches minus 40 degrees Celsius.

  However, if the operation mode is switched in the process of lowering the temperature in the tank, the temperature in the tank may temporarily rise immediately after switching.

This is because immediately after switching the cooling device to the two-way operation, the temperature of the condenser of the low temperature side refrigeration circuit is high, and the low temperature side refrigeration circuit does not function sufficiently.
That is, when performing dual operation, the low temperature side refrigeration circuit will not function unless the condenser of the low temperature side refrigeration circuit is cooled by the high temperature side evaporator. Therefore, immediately after switching the operation mode from the one-way operation to the two-way operation, the cooling capacity of the cooling device is temporarily reduced, and the temperature inside the tank is reduced despite the operation in the two-way operation. The descent speed slows down and the temperature inside the tank rises.

  Therefore, the present invention is a cooling device capable of switching between one-way operation and two-way operation, and an environmental test device in which the cooling capacity is less likely to be reduced at the time of switching and the change in temperature change gradient is less than that in the past. The issue is to provide.

  The invention described in claim 1 for achieving the above object is an environmental test apparatus having a function of cooling the inside of a tank by a cooling device, wherein the cooling device includes a low temperature side compression unit, a low temperature side condensation unit. A low-temperature side refrigeration circuit having a low-temperature side expansion unit and a low-temperature side evaporation unit, in which refrigerant circulates, a high-temperature side compression unit, a high-temperature side condensing unit, a high-temperature side expansion unit, a tank cooling evaporation unit, and a condenser cooling evaporation A high-temperature side refrigeration circuit through which the refrigerant circulates, and the condenser-cooling evaporation unit can cool the low-temperature side condensation unit, and the high-temperature side refrigeration circuit has a high-temperature side compression unit, a high-temperature side condensation unit, High-temperature side expansion unit, single-unit operation for passing the refrigerant through the tank cooling evaporator and cooling the inside of the tank, high-temperature side refrigeration circuit high-temperature side compression unit, high-temperature side condensing unit, high-temperature side expansion unit, for condenser cooling The refrigerant is passed through the evaporation section to cool the low temperature side condensation section and at the low temperature side. It is possible to perform two-way operation in which the refrigerant is passed through the refrigeration circuit and cools the inside of the tank. When switching from one-way operation to two-way operation, the tank cooling evaporator and the condenser cooling temporarily A transition operation for allowing the refrigerant to pass through both of the evaporation sections is performed, and the high temperature side expansion section supplies the refrigerant to the tank cooling expansion path for supplying the refrigerant to the tank cooling evaporation section, and the condenser cooling evaporation section. An expansion path for the condenser to be supplied; the expansion path for cooling the inside of the tank can change a passage area of the refrigerant; the expansion path for the condenser can open and close the passage path of the refrigerant; The environmental test apparatus is characterized in that the expansion path for the vessel is opened and the passage area of the refrigerant in the expansion path for cooling in the tank is reduced.

In the environmental test apparatus according to the present invention, when switching from the one-way operation to the two-way operation, a transition operation is performed in which the refrigerant is temporarily passed through both the tank cooling evaporator and the condenser cooling evaporator. Therefore, immediately after the two-way operation is started, the refrigerant continues to be supplied to the high-temperature tank cooling evaporation section, and the high-temperature tank cooling evaporation section maintains a certain level of cooling function. For this reason, the phenomenon that the temperature in the tank rises hardly occurs.
Moreover, in the environmental test apparatus of this invention, the passage area of the refrigerant | coolant of the expansion path for tank cooling is restrict | squeezed at the time of transfer operation. Therefore, it is possible to balance the amount of refrigerant flowing through the expansion path for condenser and the amount of refrigerant flowing through the expansion path for cooling inside the tank.

  The invention according to claim 2 is characterized in that, in the transition operation, the passage area of the refrigerant in the expansion path for cooling the tank is gradually reduced, and the expansion path for cooling the tank is fully closed after a lapse of a certain time. The environmental test apparatus according to claim 1.

  According to the present invention, since the rapid change of the cooling capacity is suppressed, the rapid change of the temperature change gradient is reduced.

  The invention according to claim 3 has an outside air temperature detecting means for detecting the outside air temperature, and when the outside air temperature when switching from the one-way operation to the two-way operation is equal to or higher than a certain temperature, the outside air temperature is less than a certain temperature. 3. The environmental test apparatus according to claim 1, wherein a passage area of the refrigerant in the expansion path for cooling the inside of the tank is reduced as compared with a certain case.

The present invention is an invention that can contribute to miniaturization of an environmental test apparatus, and in particular, an invention that can achieve miniaturization of a high-temperature side condensing part.
As a basic configuration of the present invention (Claim 1), a transition operation is performed when switching from a one-way operation to a two-way operation, and the refrigerant is temporarily passed through both the tank cooling evaporator and the condenser cooling evaporator. It is.
Here, when the refrigerant is supplied to the evaporator for cooling the condenser while maintaining the amount of refrigerant supplied to the evaporator for cooling the tank during the unitary operation, the amount of refrigerant circulating in the high-pressure side refrigeration circuit is reduced. As a result, the load applied to the high temperature side condensing part increases. As a result, the refrigerant pressure on the high temperature side including the high temperature side condensing part rises, the pressure on the high temperature side including the high temperature side condensing part exceeds the design pressure, and the high pressure side circuit may be damaged. Otherwise, it may cause a compressor failure.
As a means for solving this problem, a method of enlarging the condenser to withstand the condensing load during the transition operation (hereinafter, increasing the size of the condenser) can be considered.
As another measure, during the transition operation, a measure to reduce the amount of refrigerant circulating in the high-pressure side refrigeration circuit by reducing the passage area of the expansion path for cooling the tank (hereinafter referred to as “reducing refrigerant circulation amount”) is considered. It is done.
However, the former measure by “enlarging the condenser” is not preferable because the environmental test apparatus itself is increased in size.
Further, the latter countermeasure by “decrease in the amount of circulating refrigerant” is not desirable because it reduces the cooling amount of the cooling device itself. In other words, the cooling device should be operated at full power as much as possible to contribute to the cooling of the tank, but the latter countermeasures by “decreasing the circulation rate of the refrigerant” are limited to a part of the capacity of the cooling device. It will be used and the refrigeration capacity it has cannot be used effectively.
The invention according to claim 3 is an invention developed to solve these problems.
In the environmental test apparatus of the present invention, the passage area of the refrigerant in the expansion path for cooling in the tank is changed according to the outside air temperature, thereby preventing the pressure in the high temperature side condensing part from exceeding the design pressure.
That is, the pressure in the high-temperature side condensing part has a correlation with not only the refrigerant circulation amount but also the outside air temperature. When the outside air temperature is high, the pressure inside the high-temperature side condensing part becomes high, and when the outside air temperature is low, the pressure inside the high-temperature side condensing part is high. The pressure tends to decrease.
Accordingly, the present invention provides a refrigerant passage area in the expansion path for cooling in the tank when the outside air temperature when switching from the one-way operation to the two-way operation is equal to or higher than a certain temperature, compared to when the outside air temperature is less than a certain temperature. The pressure in the condensing part on the high temperature side was prevented from rising excessively.
According to the present invention, since it is not necessary to mount a large condenser, the environmental test apparatus can be miniaturized.

  The invention according to claim 4 has a tank temperature detection means for detecting the temperature in the tank, and when the tank temperature when switching from the one-way operation to the two-way operation is less than a certain temperature, The environmental test apparatus according to any one of claims 1 to 3, wherein a passage area of the refrigerant in the expansion path for cooling the tank is reduced as compared with a case where the temperature is equal to or higher than a certain level.

As described above, the cooling device should be operated at full power as much as possible to contribute to the cooling of the tank. Therefore, when switching from the single operation to the dual operation, the cooling device can be used as an expansion path for cooling the tank. It is desirable to flow a large amount of refrigerant. For that purpose, it is desirable to maximize the refrigerant passage area of the expansion path for cooling in the tank.
However, when the refrigerant passage area of the expansion path for cooling in the tank is increased, the evaporation pressure of the refrigerant rises and the evaporation temperature of the refrigerant rises. That is, if the refrigerant passage area of the expansion path for cooling in the tank is increased, the refrigerant passage amount increases and the refrigerant evaporation amount increases, so that the total amount of heat taken by the refrigerant increases, but the refrigerant evaporation temperature increases. .
On the other hand, when switching from the one-way operation to the two-way operation or when the two-way operation is started, the temperature in the tank may already be low. Therefore, when the refrigerant passage area of the expansion path for cooling the tank is maximized, the evaporation temperature of the refrigerant becomes close to the temperature in the tank, and the temperature difference cannot be taken, so the refrigerant in the evaporation section for cooling in the tank will not evaporate. .
Therefore, in the present invention, when the temperature in the tank at the time of switching from the one-way operation to the two-way operation or when the two-way operation is started is lower than a certain temperature, compared to the case where the temperature in the tank is equal to or higher than a certain temperature. The passage area of the refrigerant in the expansion path for cooling the tank is reduced, and the evaporation temperature of the refrigerant is lowered to promote heat exchange in the evaporation section for cooling the tank.

  The expansion path for cooling in the tank is formed by connecting a plurality of capillary tubes in parallel, and it is desirable that an on-off valve is provided in series with respect to one or a plurality of capillary tubes.

  The invention of a cooling device that solves the same problem is a cooling device that cools the inside of a tank covered with a heat insulating material, and has a low temperature side compression unit, a low temperature side condensation unit, a low temperature side expansion unit, and a low temperature side evaporation unit. A low temperature side refrigeration circuit in which the refrigerant circulates, and a high temperature side refrigeration circuit in which the refrigerant circulates, including a high temperature side compression unit, a high temperature side condensing unit, a high temperature side expansion unit, a tank cooling evaporation unit, and a condenser cooling evaporation unit The low temperature side condensing part can be cooled by the condenser cooling evaporating part, and the refrigerant is provided in the high temperature side compressing part, the high temperature side condensing part, the high temperature side expanding part, and the tank cooling evaporating part of the high temperature side refrigeration circuit. The refrigerant is passed through the high-temperature side compressor, high-temperature side condensing unit, high-temperature side expansion unit, and condenser cooling evaporator in the high-temperature side refrigeration circuit, and the low-temperature side condensing unit Dual operation to cool and cool the inside of the tank by passing the refrigerant through the low temperature side refrigeration circuit; When switching from the one-way operation to the two-way operation, a transition operation for temporarily passing the refrigerant through both the tank cooling evaporator and the condenser cooling evaporator is performed, and the high temperature side The expansion section has an expansion path for cooling the tank for supplying refrigerant to the evaporation section for cooling the tank, and an expansion path for condenser for supplying the refrigerant to the evaporation section for cooling the condenser. The refrigerant passage area can be changed, and the condenser expansion path can open and close the refrigerant passage path. In the transition operation, the condenser expansion path is opened and the refrigerant passage area of the tank cooling expansion path is opened. Is characterized by being narrowed down.

  According to the present invention, a phenomenon in which the temperature in the tank temporarily rises during the process of lowering the temperature in the tank is unlikely to occur.

  The environmental test apparatus and the cooling apparatus of the present invention have a small decrease in the cooling capacity when switching from the one-way operation to the two-way operation, and the change in the temperature change gradient is less than that in the prior art.

It is sectional drawing of the environmental test apparatus of embodiment of this invention. It is an operation | movement principle figure of the cooling device mounted in the environmental test apparatus of FIG. FIG. 3 is an operation principle diagram in which a refrigerant flow in a single operation of the cooling device of FIG. 2 is represented by a bold line. It is an operation principle figure which expressed the flow of the refrigerant at the time of the transfer operation of the cooling device of Drawing 2 by the thick line, and shows the flow of the refrigerant in the 1st stage. It is an operation principle figure which expressed the flow of the refrigerant at the time of transfer operation of the cooling device of Drawing 2 by the thick line, and shows the flow of the refrigerant in the 2nd stage. It is an operation principle figure which expressed the flow of the refrigerant at the time of the transfer operation of the cooling device of Drawing 2 by the thick line, and shows the flow of the refrigerant in the 3rd stage. It is an operation principle figure which expressed the flow of the refrigerant at the time of a shift operation of the cooling device of Drawing 2 with the thick line, and shows the flow of the refrigerant in the 4th stage. It is an operation principle figure which expressed the flow of the refrigerant at the time of a shift operation of the cooling device of Drawing 2 with the thick line, and shows the flow of the refrigerant in the 5th stage. It is the operation | movement which represented the flow of the refrigerant | coolant at the time of carrying out the dual operation of the cooling device of FIG. 2 with the thick line. It is the graph which measured the relationship between the passage of time and the temperature in a test room at the time of changing the test room of the environmental test apparatus of this embodiment from a high temperature state to a low temperature state. This graph shows the relationship between the time elapsed and the temperature in the test chamber when the test chamber of the environmental test device is changed from a high temperature state to a low temperature state. Shows the case of switching to dual operation. Measured the relationship between the temperature in the test chamber and the refrigerant pressure in the high-temperature side condensing section when the test chamber of the environmental test apparatus of the present embodiment is changed from a high temperature state to a low temperature state under the condition that the outside air temperature is high. It is a graph. It is a graph in which the relationship between the temperature in the test chamber and the pressure of the refrigerant in the high-temperature side condensing part when the test chamber of the environmental test apparatus is changed from a high temperature state to a low temperature state under the condition that the outside air temperature is high, The case where the cooling device is switched from the one-way operation to the two-way operation without going through the transition operation is shown. The environmental test apparatus of this embodiment was operated in a unified manner to create a low temperature environment in the test chamber, and the relationship between the temperature in the test chamber and the evaporation temperature of the refrigerant was measured when switching to the dual operation through the transition operation. It is a graph. This is a graph showing the relationship between the temperature in the test chamber and the evaporation temperature of the refrigerant when the environmental test equipment is operated in a single operation to create a low-temperature environment in the test chamber and then switched to dual operation without going through the transition operation. is there.

Hereinafter, specific examples of the present invention will be described.
The environmental test apparatus 1 of the present embodiment is small and has a size that can be installed on a table. The basic configuration of the environmental test apparatus 1 has a heat insulating tank 3 covered with a heat insulating wall 2 as shown in FIG. A test chamber 5 is formed in a part of the heat insulating tank 3. The test chamber 5 is a space for installing a device under test.
The environmental test apparatus 1 further includes a humidifier 6, a cooling device 7, a heater 8, and a blower 10.
The environmental test apparatus 1 has an air flow path 15 that communicates with the test chamber 5, and the humidification device 6, the cooling device 7, the heater 8, and the blower 10 are provided in the air flow path 15. . Further, a temperature sensor (tank temperature detecting means) 12 and a humidity sensor 13 are provided on the outlet side of the air flow path 15. In the environmental test apparatus 1, an air conditioner 17 is configured by the members in the air flow path 15 described above, the temperature sensor 12, and the humidity sensor 13.
In addition, the environmental test apparatus 1 of the present embodiment includes an outside air temperature sensor (outside air temperature detecting means) 18 that detects an external temperature.
The environment test apparatus 1 can create a desired temperature / humidity environment in the test chamber 5 (the heat insulating tank 3) by the air conditioner 17.

The cooling device 7 employed in the environmental test apparatus 1 according to the embodiment of the present invention includes a refrigeration circuit as shown in FIG.
Hereinafter, the refrigeration circuit of the cooling device 7 will be described.
The cooling device 7 employed in the environmental test apparatus 1 of the present embodiment includes a low temperature side refrigeration circuit 20 and a high temperature side refrigeration circuit 21.
The low temperature side refrigeration circuit 20 is a circuit drawn on the outer peripheral side in the operation principle diagram, and includes a low temperature side compression unit 22, a low temperature side refrigerant precooling unit 23, a low temperature side condensing unit 25, a low temperature side expansion unit 26, and a low temperature side. It has the evaporation part 27, and these are connected cyclically | annularly.

Here, the low temperature side compression unit 22 is a known compressor. The low temperature side refrigerant | coolant pre-cooling part 23 is a well-known air cooling type heat exchanger, and a refrigerant | coolant passes.
The low temperature side condensation part 25 comprises a part of low temperature side freezing circuit 20, and is a site | part which introduce | transduces and liquefies the compressed refrigerant gas.
The low temperature side expansion part 26 is a capillary tube.
The low-temperature side evaporator 27 is a known evaporator, and is installed in the air flow path 15 that is integrated with a tank cooling evaporator 33 described later and communicates with the test chamber 5.

The high temperature side refrigeration circuit 21 is a circuit drawn on the inner peripheral side in the operation principle diagram, and includes a high temperature side compression unit 30, a high temperature side condensation unit 31, a high temperature side expansion unit 32, a tank cooling evaporation unit 33, and condensation. This is a high-temperature side refrigeration circuit having an evaporator-cooling evaporator 35 in which the refrigerant circulates.
In the present embodiment, the tank cooling evaporator 33 and the condenser cooling evaporator 35 are connected in parallel to the high temperature side compressor 30.
The high temperature side expansion section 32 is largely divided into an expansion path 36 for cooling the tank and an expansion path 37 for the condenser. The tank cooling expansion path 36 is connected to the tank cooling evaporation section 33, and the condenser expansion path 37 is connected to the condenser cooling evaporation section 35.

The high temperature side compression unit 30 is a known compressor. The high temperature side condensing unit 31 is a known condenser. In the present embodiment, the high temperature side condensing unit 31 and the low temperature side refrigerant precooling unit 23 are disposed adjacent to each other, and are blown by the same blower 38 to perform heat exchange.
The high temperature side expansion portion 32 is a portion surrounded by a one-dot chain line in the operation principle diagram, and is constituted by a plurality of capillary tubes. In this embodiment, it is composed of six capillary tubes.

  For convenience of explanation, six capillary tubes are composed of a capillary tube for condenser 40, a first capillary tube for cooling in a tank (hereinafter referred to as a first capillary tube) 41, and a second capillary tube for cooling in a tank (hereinafter referred to as a second capillary tube). 42, a third capillary tube for cooling in the tank (hereinafter referred to as third capillary tube) 43, a fourth capillary tube for cooling in the tank (hereinafter referred to as fourth capillary tube) 44, and a fifth capillary tube for cooling in the tank (hereinafter referred to as the second capillary tube). 5 capillary tube) 45.

Of the six capillary tubes described above, only the condenser capillary tube 40 functions as the condenser expansion path 37, and the other five capillary tubes all function as the in-vessel cooling expansion path 36.
All of the five capillary tubes 41, 42, 43, 44, 45 constituting the in-tank cooling expansion path 36 have the same opening cross-sectional area. The opening cross-sectional area of the condenser capillary tube 40 is larger than the opening cross-sectional area of the capillary tubes 41, 42, 43, 44, 45 constituting the tank cooling expansion path 36.

  The tank cooling evaporator 33 is a known evaporator, and is integrated with the low temperature side evaporator 27 and installed in the air flow path 15 communicating with the test chamber 5.

  The condenser cooling evaporator 35 is a space for vaporizing the refrigerant, and is integrated with the low-temperature side condenser 25 to constitute a cascade condenser 46. Therefore, the low temperature side condensing unit 25 can be cooled by the cold heat generated by the condenser cooling evaporating unit 35.

The piping system of the high temperature side refrigeration circuit 21 is somewhat complicated. Starting from the high temperature side compression unit 30, the high temperature side condensing unit 31, the high temperature side expansion unit 32, the in-vessel cooling expansion path 36, and the in-bath cooling evaporating unit 33. The main circuit 50 returning to the high temperature side compression unit 30 and the high temperature side compression unit 30 as a starting point, the high temperature side condensation unit 31, the condenser expansion path 37 of the high temperature side expansion unit 32, and the condenser cooling evaporation unit 35 The auxiliary circuit 51 returns to the high temperature side compression unit 30 around.
A check valve 47 is provided between the condenser cooling evaporator 35 of the auxiliary circuit 51 and the high temperature side compressor 30.

  Further, there is a branch portion 53 between the main circuit 50 and the auxiliary circuit 51, and the main circuit side opening / closing valve 55 and the auxiliary circuit side opening / closing are respectively provided downstream from the branch portion 53 (based on the refrigerant flow direction). A valve 56 is provided. Both the main circuit side opening / closing valve 55 and the auxiliary circuit side opening / closing valve 56 are electromagnetic valves.

Further, as described above, the in-vessel cooling expansion path 36, which is the expansion section on the main circuit 50 side, is constituted by the five capillary tubes 41, 42, 43, 44, 45, all of which are branched pipes. Are piped in parallel.
Except for the branch pipe that reaches the fifth capillary tube 45, the branch pipes are provided with on-off valves 60, 61, 62, and 63, respectively. These are all connected in series to the capillary tubes 41, 42, 43, 44.
For convenience of explanation, the on-off valve 60 connected to the pipe connected to the first capillary tube 41 is referred to as a first on-off valve 60, and the on-off valve 61 connected to the pipe connected to the second capillary tube 42 is referred to as the second on-off valve 61. The on-off valve 62 connected to the pipe connected to the third capillary tube 43 is referred to as a third on-off valve 62, and the on-off valve 63 connected to the pipe connected to the fourth capillary tube 44 is referred to as a fourth on-off valve 63. And

  The branch pipe to which the five capillary tubes 41, 42, 43, 44, and 45 are connected is a collection of a pipe to which the first capillary tube 41 is connected and a pipe to which the second capillary tube 42 is connected. The second middle group, which constitutes the first middle group, is a collection of piping connected to the third capillary tube 43, piping connected to the fourth capillary tube 44, and piping connected to the fifth capillary tube 45. Is configured.

At the downstream side of the two middle groups, there is a junction 70, and the downstream side is connected to the tank cooling evaporator 33.
However, a part of the pipe from the junction 70 to the tank cooling evaporator 33 is in contact with the return pipe 71 that returns from the tank cooling evaporator 33 to the high temperature side compressor 30. The reason for this is to cool the refrigerant returning from the tank cooling evaporator 33 to the high temperature side compression unit 30 and prevent the excessively high temperature refrigerant from flowing into the high temperature side compression unit 30.

The cooling device 7 of this embodiment can be operated in a single operation. The unitary operation is an operation mode in which the refrigerant is circulated only in the main circuit 50 of the high temperature side refrigeration circuit 21. That is, when performing a one-way operation, only the high temperature side compression unit 30 is activated and the low temperature side compression unit 22 is stopped.
The flow of the refrigerant in the single operation is as shown in FIG. That is, the high temperature side compression unit 30 is started and all the on-off valves 55, 60, 61, 62, 63 belonging to the main circuit 50 are opened, and the on-off valve (auxiliary circuit side on-off valve 56) belonging to the auxiliary circuit 51 is closed. As a result, starting from the high temperature side compression unit 30, the refrigerant flows into the high temperature side condensing unit 31, the expansion passage 36 for cooling in the tank of the high temperature side expansion unit 32, and the evaporation unit 33 for cooling in the tank, and the evaporation unit for cooling in the tank The surface temperature of 33 falls and the inside of a test tank is cooled.

Further, the cooling device 7 of the present embodiment can be operated in a two-way operation. The dual operation is an operation mode performed by circulating a refrigerant through the auxiliary circuit 51 of the high temperature side refrigeration circuit 21 and the low temperature side refrigeration circuit 20. That is, when performing the dual operation, both the high temperature side compression unit 30 and the low temperature side compression unit 22 are activated.
The flow of the refrigerant in the dual operation is as shown in FIG. That is, the high temperature side compression unit 30 is started, all the on-off valves 55, 60, 61, 62, 63 belonging to the main circuit 50 are closed, and the auxiliary circuit-side on-off valve 56 belonging to the auxiliary circuit 51 is opened. As a result, the auxiliary circuit 51 returns to the high temperature side compression unit 30 from the high temperature side compression unit 30 through the high temperature side condensation unit 31, the condenser expansion path 37 of the high temperature side expansion unit 32, and the condenser cooling evaporation unit 35. Then, the refrigerant flows to cool the low temperature side condensing part 25 constituting the cascade condenser 46.

On the other hand, when the low temperature side compression unit 22 is activated, the refrigerant circulates in the low temperature side refrigeration circuit 20, and the low temperature side refrigerant precooling unit 23, the low temperature side condensing unit 25, and the low temperature side expansion start from the low temperature side compression unit 22. The refrigerant flows through the section 26 and the low temperature side evaporation section 27. The refrigerant gas that has been compressed by the low temperature side compression unit 22 and brought to a high temperature state is somewhat cooled by the low temperature side refrigerant precooling unit 23. And a refrigerant | coolant flows into the low temperature side condensation part 25, is cooled and condensed, and also temperature falls and it will be in a supercooled state.
The condensed refrigerant passes through the constriction portion at the low temperature side expansion portion 26 and expands at the low temperature side evaporation portion 27. As a result, the low-temperature refrigerant evaporates in the low-temperature side evaporation unit 27, and the inside of the test chamber 5 (the heat insulating tank 3) is cooled.

Further, the cooling device 7 of the present embodiment performs the transition operation when switching from the one-way operation to the two-way operation. In the transfer operation, the refrigerant is supplied to both the main circuit 50 and the auxiliary circuit 51 of the high temperature side refrigeration circuit 21, and the refrigerant is also circulated through the low temperature side refrigeration circuit 20 in this state.
Further, in the cooling device 7 of the present embodiment, the transition operation is performed in stages.
That is, in the transition operation, as described above, the refrigerant is also passed through the main circuit 50 of the high-temperature side refrigeration circuit 21, but the passage area of the refrigerant in the expansion passage 36 for cooling in the tank, which is the expansion portion of the main circuit 50, is increased with time. Change.
Specifically, all the flow paths that pass through the five capillary tubes 41, 42, 43, 44, 45 constituting the in-vessel cooling expansion path 36 are initially opened, and one by one with the passage of time. close up. And the passage area of the refrigerant | coolant of the expansion path 36 for tank cooling is gradually reduced. Then, the passages that pass through the five capillary tubes 41, 42, 43, 44, 45 are fully closed after a certain period of time.

In the present embodiment, the operation is performed in the state of the first stage immediately after switching from the one-way operation to the two-way operation. That is, in the first stage immediately after switching from the one-way operation to the two-way operation, as shown in FIG. 4, all five capillary tubes 41, 42, 43, 44, 45 constituting the tank cooling expansion path 36 have a refrigerant. Pass through. That is, the main circuit-side on-off valve 55 is opened, and the first on-off valve 60, the second on-off valve 61, the third on-off valve 62, and the fourth on-off valve 63 are all opened.
As a result, the tank cooling expansion path 36 is fully opened, and the cooling capacity of the tank cooling evaporator 33 belonging to the high temperature side refrigeration circuit 21 is maintained.
On the other hand, the auxiliary circuit side opening / closing valve 56 is also opened, and the refrigerant flows into the auxiliary circuit 51, so that the low temperature side condensing unit 25 constituting the cascade condenser 46 is cooled. For this reason, the low-temperature side evaporator 27 belonging to the low-temperature side refrigeration circuit 20 also exhibits a cooling capacity.
For this reason, in the first stage transition operation, the tank cooling expansion path 36 is fully open, the cooling capacity of the tank cooling evaporator 33 belonging to the high temperature side refrigeration circuit 21 is maintained at a considerably high level, and Some refrigerant also flows through the circuit 51, and the low-temperature side evaporation unit 27 also develops cooling capacity.
Accordingly, in the first stage, there is no significant change in the cooling capacity of the cooling device 7. At least immediately after switching, the cooling capacity is not greatly reduced.

When a certain time has elapsed, the transition operation shifts to the second stage. In the second stage, the flow passes through the first capillary tube 41 among the flow paths that pass through the five capillary tubes 41, 42, 43, 44, 45 constituting the in-vessel cooling expansion path 36 as shown in FIG. 5. The flow path is closed.
That is, the main circuit side opening / closing valve 55 is kept open and the first opening / closing valve 60 is closed. The second on-off valve 61, the third on-off valve 62, and the fourth on-off valve 63 are kept open.
As a result, the expansion path 36 for cooling in the tank is in a “four-fifth open” state, and the cooling capacity of the evaporation section 33 for cooling in the tank belonging to the high-temperature side refrigeration circuit 21 is somewhat reduced but maintained considerably.
The auxiliary circuit side opening / closing valve 56 is also opened, so that the refrigerant flows into the auxiliary circuit 51, and the low temperature side condensing part 25 constituting the cascade condenser 46 is cooled. For this reason, the low-temperature side evaporator 27 belonging to the low-temperature side refrigeration circuit 20 also exhibits a cooling capacity. Further, since the amount of refrigerant flowing into the auxiliary circuit 51 is somewhat increased, the refrigeration capacity of the low temperature side evaporator 27 is slightly increased.

Further, when a certain time elapses, the shift operation shifts to the third stage. In the third stage, the first capillary tube 41 and the second of the flow paths that pass through the five capillary tubes 41, 42, 43, 44, 45 constituting the in-vessel cooling expansion path 36 as shown in FIG. 6. The flow path passing through the capillary tube 42 is closed.
The tank cooling expansion path 36 is in a “three-fifth open” state, and the cooling capacity of the tank cooling evaporator 33 belonging to the high-temperature side refrigeration circuit 21 is halved compared to when fully opened.
On the other hand, the amount of refrigerant flowing through the auxiliary circuit 51 increases, and the low-temperature side condensing unit 25 is further cooled. Therefore, although the cooling capacity of the tank cooling evaporator 33 belonging to the high temperature side refrigeration circuit 21 is reduced, the refrigeration capacity of the low temperature side evaporator 27 is increased.

Further, when a certain time elapses, the shift operation shifts to the fourth stage. In the fourth stage, the first capillary tube 41 and the second of the flow paths passing through the five capillary tubes 41, 42, 43, 44, 45 constituting the in-vessel cooling expansion path 36 as shown in FIG. The flow paths passing through the capillary tube 42 and the third capillary tube 43 are closed.
The tank cooling expansion path 36 is in a “two-fifth open” state, and the cooling capacity of the tank cooling evaporator 33 belonging to the high temperature side refrigeration circuit 21 is reduced.
On the other hand, the amount of refrigerant flowing through the auxiliary circuit 51 is significantly increased, and the low temperature side condensing unit 25 is further cooled. Therefore, although the cooling capacity of the tank cooling evaporator 33 belonging to the high temperature side refrigeration circuit 21 is further reduced, the refrigeration capacity of the low temperature side evaporator 27 is further increased.

Further, when a certain time has elapsed, the shift operation shifts to the fifth stage. In the fifth stage, the first capillary tube 41 and the second of the flow paths passing through the five capillary tubes 41, 42, 43, 44, 45 constituting the in-vessel cooling expansion path 36 as shown in FIG. The flow paths passing through the capillary tube 42, the third capillary tube 43, and the fourth capillary tube 44 are closed. The main circuit side opening / closing valve 55 is kept open. Since the branch pipe to which the fifth capillary tube 45 belongs does not have an open / close valve, the refrigerant flows through the fifth capillary tube 45.
However, the tank cooling expansion path 36 is in the “one-fifth open” state, and the cooling capacity of the tank cooling evaporator 33 belonging to the high temperature side refrigeration circuit 21 is extremely small.
On the other hand, the amount of refrigerant flowing through the auxiliary circuit 51 is further greatly increased, and the low temperature side condensing unit 25 is cooled more powerfully. Therefore, although the cooling capacity of the in-vessel cooling evaporator 33 belonging to the high temperature side refrigeration circuit 21 is almost lost, the refrigeration capacity of the low temperature side evaporator 27 is close to full power.

When a certain time further elapses, the main circuit side on-off valve 55 is closed and the refrigerant flowing into the main circuit 50 is stopped, and a complete two-way operation as shown in FIG. 9 is started.
The time during which the transition operation is performed is about 2 to 6 minutes. In addition, it is recommended that the time for performing the transition operation is about 3 to 5 minutes.
The execution time of each stage is about 60 seconds to 200 seconds. It is desirable to perform the initial stage relatively long.
For example, after executing the first stage for 80 seconds, the process proceeds to the second stage, and the second stage is executed for 40 seconds. Further, the third stage is executed for 40 seconds, the fourth stage is executed for 40 seconds, and the fifth stage is executed for 40 seconds. As a result, the transition operation is performed for 240 seconds, and the operation is switched to the dual operation.

  In principle, in the cooling device 7 of the present embodiment, the stage advances sequentially from the first stage, and shifts to a complete dual operation. However, when specific conditions are met, some stages are skipped and a two-way operation is performed.

  One of the conditions for skipping the stage is the outside air temperature. The environmental test apparatus of the present embodiment has an “outside temperature correction function”. When the outside temperature is high, the first stage or the first and second stages are skipped, and the transition operation is performed from the second stage or the third stage. To start.

That is, when the outside air temperature is high, the condensing temperature is increased by an amount corresponding to the outside air temperature, so that the refrigerant pressure in the high temperature side condensing unit 31 increases.
On the other hand, about the high temperature side condensation part 31, there exists the driving | running condition assumed at the time of design, and the pressure in the high temperature side condensation part 31 is one of them. Therefore, if the pressure in the high-temperature side condensing part 31 rises excessively, the upper limit of the pressure assumed at the time of design may be exceeded, and there is a risk of damage to the high-pressure circuit. Can cause
Therefore, the pressure in the high temperature side condensing part 31 needs to be maintained below a certain level.

On the other hand, in the first stage of the transition operation, the expansion path 37 for the condenser is opened in addition to the expansion path 36 for cooling in the tank being fully opened. For this reason, the amount of refrigerant flowing through the high temperature side refrigeration circuit 21 increases, and this increases the pressure of the high temperature side condensing unit 31.
Therefore, if the first stage is operated when the outside air temperature is high, the pressure in the high-temperature side condensing unit 31 exceeds the upper limit of the pressure assumed at the time of design.

Therefore, in this embodiment, the outside temperature sensor (outside temperature detecting means) 18 is monitored, and if the detected temperature of the outside temperature sensor 18 is equal to or higher than a certain temperature, the transition operation is started from the second stage or the third stage.
For example, if the detected temperature of the outside air temperature sensor 18 is equal to or higher than the first outside air reference temperature, the transition operation is started from the second stage. If the temperature detected by the outside air temperature sensor 18 is equal to or higher than the second outside air reference temperature, the transition operation is started from the third stage.

Another condition for skipping the stage is the temperature inside the tank.
The environmental test apparatus of the present embodiment has a “vessel temperature correction function”. When the bath temperature is low, the first stage or the first and second stages are skipped, and the second stage or the third stage is used. Start transition operation.

As described above, in the first stage of the transition operation, the expansion path 37 for the condenser is opened in addition to the expansion path 36 for cooling in the tank being fully opened. As a result, the evaporation pressure of the refrigerant increases and the evaporation temperature of the tank cooling evaporator 33 increases. Therefore, when the operation is performed in the state of the first stage when the temperature in the tank is already low, the evaporation temperature of the evaporation unit 33 for cooling in the tank may exceed the temperature in the tank.
Therefore, in the cooling device 7 employed in the present embodiment, the temperature sensor 12 provided in the test chamber 5 is monitored, and the transition operation is performed in the second stage or the third stage if the temperature detected by the temperature sensor 12 is less than a certain level. Start with
For example, if the detected temperature of the temperature sensor 12 is lower than the first tank reference temperature, the transition operation is started from the third stage. If the temperature detected by the temperature sensor 12 is equal to or higher than the first tank reference temperature and lower than the second tank reference temperature, the transition operation is started from the second stage.

The first tank reference temperature is desirably about minus 10 degrees Celsius to plus 10 degrees Celsius, and the second tank reference temperature is desirably about 40 degrees Celsius to 70 degrees Celsius.
Actually, both the outside air reference temperature and the inside tank reference temperature are monitored, and the start stage is selected more finely. Of course, only one of the outside air reference temperature and the tank reference temperature may be monitored.

  In the embodiment described above, the tank cooling expansion path 36 is configured by the plurality of capillary tubes 41, 42, 43, 44, 45, but an expansion valve is used instead of the capillary tubes 41, 42, 43, 44, 45. May be used. The same applies to the condenser capillary tube 40 provided in the condenser expansion path 37 and can be replaced with an expansion valve.

  In addition, in the transfer operation, all the flow paths that pass through the five capillary tubes 41, 42, 43, 44, and 45 are first opened and then closed one by one over time. You may close the flow path which passes 41, 42, 43, 44, 45 simultaneously.

In the above-described embodiment, the in-vessel cooling expansion path 36 is configured with five capillary tubes 41, 42, 43, 44, 45, but the number of capillary tubes is arbitrary and may be less than 5, It may be 6 or more.
The appropriate number of capillary tubes is about 3 to 8.
In the above-described embodiment, capillary tubes having the same opening diameter are used. However, capillary tubes having different opening diameters may be mixed.

In the above-described embodiment, the main circuit 50 is provided with the main circuit side opening / closing valve 55, and the main circuit 50 is opened / closed by the main circuit side opening / closing valve 55. Further, for the purpose of ensuring the minimum refrigerant flow rate when the main circuit side opening / closing valve 55 is opened, no opening / closing valve is provided in the branch pipe leading to the fifth capillary tube 45.
As a modified example, a configuration in which the main circuit side opening / closing valve 55 is omitted and a separate opening / closing valve is provided in the branch pipe leading to the fifth capillary tube 45 instead is conceivable.

Next, experiments conducted by the inventors will be described.
(1) Comparison of temperature drop gradient The apparatus shown in FIG. 1 was adopted as the environmental test apparatus of this embodiment, and the temperature in the tank was changed from an environment of 150 degrees Celsius to an environment of minus 40 degrees Celsius. Switching from the one-way operation to the two-way operation was performed when the temperature in the tank was 50 degrees Celsius, and a transition operation was performed when switching from the one-way operation to the two-way operation. The transition operation was started from the first stage, the stages were sequentially raised, and after the fifth stage, the operation was shifted to a complete dual operation.
The relationship between the temperature in the tank and the time at that time is as shown in FIG. 10, and the temperature decrease curve was different between the one-way operation and the two-way operation, but the switching was smooth.

On the other hand, the environmental test apparatus having the same mechanical structure was used, and the switching from the single operation to the dual operation was performed without going through the transition operation.
The relationship between the temperature in the tank and the time at that time is as shown in FIG. 11, and the temperature in the tank was temporarily increased at the time of switching, and the switching lacked smoothness.

(2) Comparison of the pressure in the high temperature side condensing part 31 The apparatus shown in FIG. 1 was employ | adopted as an environmental test apparatus of this embodiment. The design upper limit pressure of the high temperature side condensing part 31 of the environmental test apparatus 1 is 2.6 MPa.
The apparatus used for the experiment has an “outside temperature correction function”. When the outside temperature is high, the first stage or the first and second stages are skipped, and the transition operation is started from the second stage or the third stage. To do.
The temperature in the vicinity of the environmental test apparatus was 35 degrees Celsius.

The temperature inside the tank was changed from an environment of 150 degrees Celsius to an environment of minus 40 degrees Celsius. Switching from the single operation to the dual operation was performed when the temperature in the tank was about 60 degrees Celsius. The transition operation was performed when switching from the one-way operation to the two-way operation, but the transition operation was performed from the second stage. Then, the stage was moved up sequentially, and after the fifth stage, it was shifted to a complete dual operation.
The relationship between the temperature in the tank and the pressure of the refrigerant in the high-temperature side condensing unit 31 is as shown in FIG. 12, and the pressure of the refrigerant in the high-temperature side condensing unit 31 increases during the transition operation. The upper limit pressure of 2.6 MPa was not exceeded.

On the other hand, the environmental test apparatus having the same mechanical structure was used, and the switching from the one-way operation to the two-way operation was performed through the transition operation, but the transition operation was performed from the first stage as a rule. Then, the stage was moved up sequentially, and after the fifth stage, it was shifted to a complete dual operation.
The relationship between the temperature in the tank and the pressure of the refrigerant in the high-temperature side condensing unit 31 at that time is as shown in FIG. The situation exceeded the pressure of 2.6 MPa.

(3) Comparison between tank temperature and refrigerant evaporation temperature The apparatus shown in FIG. 1 was adopted as the environmental test apparatus of this embodiment.
The apparatus used in the experiment has a “vessel temperature correction function”. When the bath temperature is low, the first stage or the first and second stages are skipped, and the operation is shifted from the second stage or the third stage. To start.

  The temperature inside the tank was changed from an environment of minus 15 degrees Celsius to an environment of minus 40 degrees Celsius. Switching from one-way operation to two-way operation was performed when the temperature in the tank was minus 15 degrees Celsius. The transition operation was performed when switching from the one-way operation to the two-way operation, but the transition operation was performed from the second stage. Then, the stage was moved up sequentially, and after the fifth stage, it was shifted to a complete dual operation.

The relationship between the temperature in the tank and the evaporation temperature of the refrigerant (the high temperature side refrigeration circuit 21 and the low temperature side refrigeration circuit 20) is as shown in FIG. 14, and the evaporation temperature (inside the tank) of the high temperature side refrigeration circuit 21 during the transition operation. Although the cooling evaporator 33 side) rises, the evaporation temperature of the high temperature side refrigeration circuit 21 does not exceed the in-tank temperature.
That is, when attention is paid to the high temperature side refrigeration circuit 21, the evaporating temperature of the high temperature side refrigeration circuit 21 (on the side of the tank cooling evaporator 33 side) temporarily rises in the transition operation in the process of switching from the single operation to the dual operation. Then decline. When the operation is completely switched to the dual operation, the refrigerant does not flow to the tank cooling evaporator 33 side.

On the other hand, when paying attention to the low temperature side refrigeration circuit 20, the transition operation is performed in the process of switching from the one-way operation to the two-way operation, the low temperature side refrigeration circuit 20 is activated, and flows through the low temperature side refrigeration circuit 20 as shown in FIG. The evaporation temperature of the refrigerant gradually decreases.
In the present embodiment, the operation state of the low-temperature side refrigeration circuit 20 becomes a steady state, and the evaporation temperature of the refrigerant flowing through the low-temperature side refrigeration circuit 20 becomes substantially stable and exhibits a desired low temperature. Since the refrigerant supply to the tank cooling evaporator 33 side is stopped, the tank temperature does not increase during the transition operation.

On the other hand, the environmental test apparatus having the same mechanical structure was used, and the switching from the one-way operation to the two-way operation was performed through the transition operation, but the transition operation was performed from the first stage as a rule. Then, the stage was moved up sequentially, and after the fifth stage, it was shifted to a complete dual operation.
The relationship between the temperature in the tank and the evaporation temperature of the refrigerant at that time is as shown in FIG. 15, and the evaporation temperature increased during the transition operation and exceeded the temperature in the tank.

DESCRIPTION OF SYMBOLS 1 Environmental test apparatus 3 Thermal insulation tank 5 Test chamber 7 Cooling apparatus 12 Temperature sensor (temperature detection means in a tank)
18 Outside temperature sensor (outside temperature detection means)
20 Low temperature side refrigeration circuit 21 High temperature side refrigeration circuit 22 Low temperature side compression unit 25 Low temperature side condensing unit 26 Low temperature side expansion unit 27 Low temperature side evaporation unit 30 High temperature side compression unit 31 High temperature side condensing unit 32 High temperature side expansion unit 33 Evaporating section 35 Evaporating section for condenser cooling 36 Expansion path for cooling in tank 37 Expansion path for condenser 40 Capillary tube (for condenser)
41, 42, 43, 44, 45 Capillary tube (for cooling inside the tank)
60, 61, 62, 63 On-off valve

Claims (6)

In the environmental test equipment with the function of cooling the inside of the tank by the cooling device,
The cooling device has a low temperature side compressor, a low temperature side condenser, a low temperature side expansion unit, and a low temperature side evaporator, and a low temperature side refrigeration circuit in which refrigerant circulates;
A high temperature side compression unit, a high temperature side condensation unit, a high temperature side expansion unit, a tank cooling evaporation unit, and a condenser cooling evaporation unit, and a high temperature side refrigeration circuit through which a refrigerant circulates is provided,
The condenser on the low temperature side can be cooled by the evaporator for cooling the condenser,
A unitary operation in which the refrigerant is passed through the high-temperature side refrigeration circuit of the high-temperature side refrigeration circuit, the high-temperature side condensing unit, the high-temperature side expansion unit, and the tank cooling evaporator to cool the inside of the tank;
Pass the refrigerant through the high temperature side compressor, high temperature side condensing unit, high temperature side expansion unit and condenser cooling evaporator of the high temperature side refrigeration circuit to cool the low temperature side condensing unit and pass the refrigerant through the low temperature side refrigeration circuit. It is possible to perform dual operation to cool the inside of the tank,
When switching from the one-way operation to the two-way operation, a transition operation is performed in which the refrigerant is temporarily passed through both the tank cooling evaporator and the condenser cooling evaporator,
The high temperature side expansion section has a tank cooling expansion path for supplying refrigerant to the tank cooling evaporation section, and a condenser expansion path for supplying refrigerant to the condenser cooling evaporation section. The expansion path can change the passage area of the refrigerant,
The expansion path for the condenser can open and close the passage path of the refrigerant,
In the transition operation, the expansion path for the condenser is opened and the passage area of the refrigerant in the expansion path for cooling in the tank is reduced.   2. The environment according to claim 1, wherein, in the transition operation, the passage area of the refrigerant in the expansion path for cooling the tank is gradually reduced, and the expansion path for cooling the tank is fully closed after a predetermined time has elapsed. Test equipment.   When there is an outside air temperature detection means for detecting the outside air temperature, and the outside air temperature when switching from the one-way operation to the two-way operation is higher than a certain temperature, it is for cooling in the tank compared with the case where the outside air temperature is less than a certain temperature. The environmental test apparatus according to claim 1, wherein a passage area of the refrigerant in the expansion path is reduced.   Has a tank temperature detection means for detecting the temperature in the tank, and when the tank temperature when switching from the one-way operation to the two-way operation is less than a certain temperature, compared to when the tank temperature is above a certain value The environmental test apparatus according to claim 1, wherein a passage area of the refrigerant in the expansion path for cooling the tank is reduced.   5. The expansion path for cooling in the tank is formed by connecting a plurality of capillary tubes in parallel, and an open / close valve is provided in series with respect to one or a plurality of capillary tubes. The environmental test apparatus in any one of. In the cooling device for cooling the inside of the tank covered with the heat insulating material,
A low temperature side refrigerating circuit having a low temperature side compression unit, a low temperature side condensing unit, a low temperature side expansion unit, and a low temperature side evaporation unit, in which the refrigerant circulates;
A high temperature side compression unit, a high temperature side condensation unit, a high temperature side expansion unit, a tank cooling evaporation unit, and a condenser cooling evaporation unit, and a high temperature side refrigeration circuit through which a refrigerant circulates is provided,
The condenser on the low temperature side can be cooled by the evaporator for cooling the condenser,
A unitary operation in which the refrigerant is passed through the high-temperature side refrigeration circuit of the high-temperature side refrigeration circuit, the high-temperature side condensing unit, the high-temperature side expansion unit, and the tank cooling evaporator to cool the inside of the tank;
Pass the refrigerant through the high temperature side compressor, high temperature side condensing unit, high temperature side expansion unit and condenser cooling evaporator of the high temperature side refrigeration circuit to cool the low temperature side condensing unit and pass the refrigerant through the low temperature side refrigeration circuit. It is possible to perform dual operation to cool the inside of the tank,
When switching from the one-way operation to the two-way operation, a transition operation is performed in which the refrigerant is temporarily passed through both the tank cooling evaporator and the condenser cooling evaporator,
The high temperature side expansion section has a tank cooling expansion path for supplying refrigerant to the tank cooling evaporation section, and a condenser expansion path for supplying refrigerant to the condenser cooling evaporation section. The expansion path can change the passage area of the refrigerant,
The expansion path for the condenser can open and close the passage path of the refrigerant,
In the transition operation, the condenser expansion path is opened, and the refrigerant passage area of the tank cooling expansion path is reduced.

Images